The Rocker Lever Assembly is a component of the engine valve train system that is responsible for opening and closing the engine valves. It is designed to convert the upward motion of the camshaft into a downward motion that opens the valve. The Rocker Lever Assembly is made up of a rocker arm, pushrod, and adjusting screw, and is an essential part of the engine's operation. The part number 5259953 is specific to Cummins engines.